We had some of the original 2010 Fusion Hybrids, and the Escape Hybrid here at work, quite frankly I was not that impressed considering the hybrid versions didn't get that much more MPG and were significantly more expensive.
The C-MAX was the first hybrid that really seemed to use some of the cross-licensed Toyota tech, but Ford somehow managed to make the performance of the C-MAX much nicer (I test drove a Prius V and it was sooo sluggish). The panoramic roof was a nice option that is hard to find on cars less than $30K..It was the first one that really seemed like a true hybrid to me - enough to make me want to buy one when the price dropped below $24K.
I had a Prius, and as far as I'm concerned the hatchback is still one of the best sedans out there, smooth, quiet, relatively powerful, no other 87 octane car can get 49-50MPG..
Using Li-on batteries was a risk Toyota didn't want to take because the NiMh batteries seemed safer, and more reliable - they did a lot of things like using AGM battery instead of liquid battery, to try to make things safer in a crash. Even so in 15 years of Prius being on the road people are just now starting to trust the battery packs so maybe Toyota didn't want to take that risk without more testing.
Li-on batteries can explode violently if not built and maintained properly (look at the knock offs in the news lately and the Dreamliner airplane).. So yeah it's a risk, but using those packs Ford was able to equip a much bigger vehicle, provide better performance and use EV more aggressively than Toyota. I guess that risk is part of buying the car. At least they are covering some of the faults with recalls. Even with all of the TSBs I still like my C-MAX, wish Ford would market them more aggressively but I am seeing more of them on the road now anyway.